A huge wildfire burning in the mountains above Los Angeles, the largest ever in the county, was started by arson and will be investigated as a homicide, authorities said on Thursday, Reuters reported.
The arson declaration was made after investigators found evidence of arson at the point of origin for the so-called Station Fire, which has blackened an area the size of Chicago, started.
"Arson investigators from the U.S. Forest Service (and other agencies) ... have concluded that the Station Fire was the result of an arson," Forest Service Commander Rita Wears told reporters at a press conference.
The Los Angeles County Sheriff's Department homicide bureau has initiated a homicide investigation due to the death of two firefighters, Wears said.
Containment of the so-called Station Fire increased to 38 percent, up from 28 percent a day earlier, according to fire commander Mike Dietrich, who said his force of more than 4,700 firefighters was making "great progress."
But the amount of scorched landscape grew slightly, also, to nearly 145,000 acres -- or about 226 square miles (585 sq km).
The blaze, roaring out of control since August 26 in the rugged San Gabriel Mountains overlooking the Los Angeles basin, had prompted authorities to order the evacuation of some 6,300 homes at the height of the fire threat.
As of Wednesday night, the all-clear had been given for the last of those foothill residents to return home.
But a flare-up in one canyon early on Thursday led officials to order a small cluster of homes evacuated, and fire crews were concentrating their attack on the southeastern flank of the blaze to prevent flames from spreading into several foothill communities below.
"That's our No. 1 priority for the next several days," Dietrich said late on Wednesday.
One town on the fire's southeastern fringe is Pasadena, known for its annual New Year's Day Rose Bowl college football game and Tournament of Roses Parade. Fire commanders scheduled a town meeting for Thursday night to brief Pasadena residents on the situation.
Meanwhile, fire commanders expressed confidence that key facilities on Mount Wilson, home to a world-famous observatory and a telecommunications and broadcasting hub for the region, would be spared from damage.
Days earlier, authorities had been predicting the 5,700-foot (1,740-meter) peak was virtually doomed to be engulfed in a firestorm. But subdued fire activity attributed to rising humidity gave fire crews time to launch a renewed, all-out campaign to clear dense brush around the mountain and to treat the slopes with heavy doses of fire retardant.
Despite progress made in the past three days, fire officials said they expect they will need until mid-September to achieve full containment.
The blaze has destroyed more than 60 homes, killed two firefighters and cost $21 million to battle so far, making it the most expensive of several California wildfires in recent weeks that already have more than half-depleted the cash-strapped state's emergency firefighting budget.
Governor Arnold Schwarzenegger, who paid his third visit this week to the fire zone, has insisted the state has plenty of resources at its disposal, including a newly created $500 million reserve funded primarily with social services cuts.
The aggressive use of aircraft to battle the Station Fire has contributed to much of its cost but also has been a key factor in the firefight's progress.
Dietrich said that helicopters and planes have dropped nearly 2.5 million gallons of water and fire retardant on the fire. Airplanes alone have dropped 670,000 gallons of fire-retardant chemicals.
"That's more than some of our permanent air tanker stations across the country drop in an entire year," Dietrich said.